Fiber quality parameters and within-boll yield components of Gossypium arboreum L. putative mutant lines

Abstract

This study was initiated to develop a fiberless mutant of Gossypium arboreum L. in order to identify genes that code for cellulose fiber production in cotton. The biosynthetic pathways to fiber cellulose production are still not known despite many attempts to find the precursors and enzymes involved. If these pathways were identified then they could provide useful tools for manipulating the amount and quality of cotton fibers. Gossypium arboreum, n=13, 2n=26, is a diploid Gossypium species that produces spinnable fibers and is grown commercially in parts of India today. Understanding the complex biochemical pathways of fiber production in this diploid cultivar should be directly applicable to understanding fiber production in the cultivars grown in the U.S., G. hirsutum L. and G. barbadense L., x=13, n=26, 2n=52. Gossypium arboreum seed (MO) were chemically treated with diepoxybutane (DEB) and planted as the MI generation in the field at the Texas A&M University Research Farm, College Station, Texas in 1994. Three DEB treatments were used; 5.0 mM, 7.4 MM, and 10.0 mM. Flowers were forced to self pollinate on the MI plants and the resulting bolls were hand harvested from individual plants. Seed (M2) from each plant were maintained as independent lines and planted into progeny rows in 1995. Boll samples harvested from each M2 progeny row were ginned and the seeds were acid delinted. Data collected included weight of seed cotton/M2 row, seed cotton weight/row, lint weight/row, and the weight of 100 fuzzy seed (seed index). Fiber samples of each M2 row were forwarded to the International Center for Textile Research and Development in Lubbock, Texas for high volume instrument (HVI) fiber analysis. Fiber quality parameters included: upper half mean fiber length (UBM), fiber bundle strength, micronaire, and uniformity index. Lint yield components, using the ontogenetic yield model proposed by Worley et al. included: lint percentage (LP), seeds per boll (S/BOLL), seed cotton per seed (SC/S), lint per seed (L/S), and fibers per seed (F/S). Although a completely fiberless M2 plant, which was our original goal, was not found among the 1995 progeny, M2 progeny were evaluated for variation in fiber quality and within-boll yield components. M2 lines within each treatment were classed as a putative mutant if it's individual value for any component was less than or greater than 3 standard deviation units from the mean value of the population being considered. Given this criteria, 26 putative mutant lines were identified and additional evaluations will be necessary to determine if these are true mutants or simply represent individuals from less than or equal to 1% of the population of G. arboreum.